Apparatus and method for etching metal webs



Feb. 11', 1958 N. B. `MEARs 2,822,635

APPARATUS AND METHOD FOR ETCHING METAL WEBS Filed 0G13. l, 1954 3 Sheets-Sheet 1 Feb. 11, 1958 N. B. MEARS APPARATUS AND METHOD FOR ETCHING METAL WEBS Filed 000. l. 1954 3 Sheets-Sheet 2 f m M m m5 N 4x4 .W

Feb. 11, 1958 N. B. MEARs APPARATUS AND METHOD FOR ETCHING METAL WEBS 3 Sheets-Sheet 3 `Filed Oct. l, 1954 United States Patent `O APPARATUS AND METHOD FOR ETCHING B/IETAL WEBS NormanB. Mears, Dakota County, Minn.

Application October 1, 1954, Serial No. 459,623

12 Claims. (Cl. 41-9) This invention relates to an improved apparatus and method for etching metal webs and particularly to improvements in the invention described and claimed in my application for patent Serial No. 351,127, filed April 27, 1953, now Patent #2,762,149, for Method and Apparatus for Producing Perforated Metal Webs.

Among the objects of the present invention are to increase the rate of etching and facilitate control of the sizes and shapes of minute etched perforations distributed over web, areas of large size by providing sprays of etching uid which are caused to sweep across the areas to be etched from rapidly changing directions while the Web is moved continuously through an etching zone at a controlled rate of travel.

A particular object is to provide apparatus of the class described including means for moving a thin metal web continuously at a controlled rate through an etching chamber, the web having exposed areas and masked areas defined by an etching resistant coating, in combination with one or more spray nozzles which are continuously oscillated in planes substantially perpendicular to the direction of travel of the web through the chamber whereby etching fluid from each nozzle is caused to impinge against the web in continuously changing angular directions relative to the web surface or surfaces.

Other objects will appear and be more fully pointed out in the following specification and claims.

Among the articles of manufacture which may be produced more rapidly, uniformly and at reduced cost by the present invention are aperture masks for television tubes, line screens for mechanical separation of solid particles, reticles for lire control and other precision instruments, electric shaving and clipper heads, Ventilating screens, and other articles requiring precise location of minute perforations in metal blanks. For such articles the metal web or sheet is less than .02 inch thick and is usually within the range .001 to .010 inch thick. Pure metals, e. g., iron, steel, copper, silver, nickel or tin, or combinations of such metals, such as super nickel, are best suited for accurately controlled perforation by etching ktreatment and the web should be of uniform thickness and purity. Thin webs of this character are diflicult to .handle because of their malleability, flexibility and general tendency to be locally deformed as by wrinkles, creases and other indentations which destroy the accuracy and utilityof the product.

By the present invention, adjustments to secure uniformity of the rate of etching at all points over a. large web area and to insure uniformity in the shape of apertures precisely in accordance with the pattern ofv exposed areas on the web is obtained and I make it possible to increase the rate of travel of the web through the-etching zone and thereby increase the rate of production of aper- .ture masks or other precision articles.

Referring to the accompanying drawings which illustrate, by way of example and not for the purposefof limitation, a preferred embodiment of my improved treating :apparatus:

Mice

Figure 1 is a somewhat diagrammatic top plan view of the apparatus;

Fig. 2 is a part side elevational View and part vertical sectional view showing the apparatus somewhat diagrammatically; Fig. 3 is a fragmentary sectional view, taken on the line 3 3 of Fig. 2,-showing the power-.driven pump .and connected conduits lfor the etching fluid and also the power-driven oscillating mechanism Vfor the etching sprays shown in Fig. 2;v

Fig. 4 isa vertical sectional view ytaken on the line 4--4 of Fig. 1;

Fig. 5 is a fragmentary part horizontal `sectional view and part plan viewfof 'the mechanism for adjusting the amplitude and angle of-oscillation of one of the etching spray manifolds;

Fig. 6 `is 'a detailed Vside elevational -view showing the linkage for operati-ng -a pair of the 'oscillating manifolds;

Fig. 7 is a fragmentary sectional View showing the crank-pin connectioncarried by one of the power-actuated sprocket wheels of the. oscillating mechanism;

Fig. 8 is an end viewof ithe etching chamber, showin a modifiedl form of oscillating mechanism lfor the etching fluid manifolds;

Fig. 9 is a side eleva-tional View showing details `of the amplitude adjusting- 4mechanism and indicator `quadrant mountedon an fendy wallaof an etching chamber shown -in vertical section, and

Fig. 10 is a :cross sectional view ofone of the etching manifolds.

In the drawings, .a metal web-having exposed` surface areas and protected surface areas .defined by -etchingresistant coatings isindicated by, the numeral .1.1.- This web is suitably supported for movement along .a determined path .substantially in. a vertical plane, with onelongitudinal edge elevatedV above the other. Infitsmovement-along this path the web passes successively through an etching. chamber 12, a spray chamber 13, a chamber 14 inwhichasolvent for the coating is applied, then through a .scrubber and washer, indicated diagrammatically at 15,v whereby the softenedv coating i`s removed from the web,and linally through a drying chamber 16 and between power-actuated pressure rolls 17 which are driven at a controlled, .rate to draw the web through the machine undersui'tabl'e tension. On emerging from the pressure rolls 17, the web may be cut to suitable lengths crosswise yor it may `be wound on a reelv for subsequent subdivision Vinto the required units.

A guide for the lower `edge of the webV maycomprise a channel 18 and the upper edge may be guided along an inverted V-shapedchannel .19' or by other suitable means so that the entire area of the web between .its upper and lower margins is exposed for the etching and other treatment as the web moves along a determined path.. Asmore fully describedin my Patent No. 2,762,149, above referred to, a web having, one or both sides coated with etching resistant enamel dening the designs to be etched into or through the web maybe fedA to the apparatus from a suitable reel and Vthe photo-printed; areas of the webare first subjected lto cleansingtreatment as a preliminarygto the etching treatment. The inal'icleansing treatment may comprise the spraying of rweb surfaces with water-from spray nozzles 20 (Fig. 11). It then passes into-the `etching chamber 12 throughia vertically elongated opening-2.1 in an end wall thereof` and'after thezetchingtreatment passes out through a similar opening in thezoppositenendiwall intothe spray chamber 1'3'wherewater-spraysfrom nozzles 22 are applied totheetched-surfaces. to terminate the etching ltreatment. Details-of the subsequent treatmentapparatus; form nov partofy thepresentyinvention.

As shown in Fig. 2, the pressure rolls 17 for' drawing the4 web; under.- tension:` through theA several treatment chambers may be actuated by an electric motor 23 through suitable speed reducing gearing in a housing 24 and power take-off shaft for this gearing is operatively connected to vertical shafts 25 upon whichltlierollsl'l are fixed. The speed of rotation of theserolls may be adjusted to properly regulate the duration of the etching and other treatment applied to theiweb inthe several N chambers.

Within the etching chamber 12, in laterally spaced relation to the path of the web, are manifold pipes 26 which are continuously supplied with etching uid under pressure. These pipes extend horizontally and are supported in bearings permitting oscillating movement of `each pipe about its axis. A plurality of spray nozzles 27 are carried by each of the pipes 26 and arranged to discharge etching fluid against the web as the latter moves through the etching chamber.

rlfhe nozzles are preferably designed and arranged to deliver solid conical sprays upon the webv and are spaced at regular intervals along each of the manifold pipes to cover the entire surface or surfaces to be etched. One end of each pipe is closed and the other end portion is supported in bearings in the end wall of the chamber 12 and in a bearing 28 spaced outward from the wall. As best shown in Fig. 5, an end portion 29 of each of the manifold pipes is free to turn about the pipe axis in a union fitting 30 and is supplied with etching fluid under pressure from a fixed pipe 31. Four of these pipes are shown, two at each side of the path of the web 11. Those at each side are supplied with uid from a vertical pipe 32 and each of the latter pipes is connected to a main uid supply pipe 33 extending to the delivery port of a centrifugal pump 34. This pump is driven by an electric motor 35. Etching uid is supplied to the inlet of the pump 34 through a pipe 36 having a branch 37 extending to a tank 38 and a by-pass pipe 39 extending to the pipe 33 under control of a valve 40. By closing the valve 40 maximum pressure within the capacity of the pump 34 is applied to the etching iiuid in the manifold pipes 26. Fluid under any required lower pressure at the spray nozzles may be obtained by suitable partial closing of the valve 40. Heating coils 38a Within the tank 38 may be supplied with steam or otherwise heated to maintain the temperature of the etching uid within the required elevated range.

Provision is made for continuously moving the nozzles carried by each of the pipes 26 crossways of the direction of movement of the web in the etching chamber. Thus, with the web supported in a vertical plane and moving substantially horizontally, the nozzles may be moved in vertical planes which are perpendicular to the surfaces of the web in the etching chamber. To impart continuous oscillating movement to the nozzles, as shown in Figs. 4 and 5, an arm 41 is pivotally supported on each of the pipes 26 exteriorly of the etching chamber and the free end of the arm is operatively connected through suitable linkage to an electric motor 42 (Figs. 2 and 3). The linkage shown in Figs. 1-7 inclusive comprises a vertically reciprocating rod 43 connected by a link 44 to one of the arms 41 at each side and by a link 4S to the other arm 41 at the same side of the machine. Each rod 43 is connected at its lower end by a link 46 to a crank pin 47 carried by one of a pair of sprocket wheels 48. One of these wheels is fixed on a motor-driven shaft 49 and the other is revolubly mounted on a parallel shaft 50. A chain 51 is trained on the peripheries of the wheels 48 to rotate them in unison. The arms 41 are severally connected to the pipes 26 by manually operable screws 52 and by crank arms S3 each of which is fixed at one end on one of the pipes 26. Projecting from each of the arms 53 is a pivot pin 54 formed with a screw threaded bearing for operative engagement with one of the screws 52. A second pivot pin 55 connects an end of each screw S2 vto the associated arm 41. By turning the screws 52, the

4travel through the etching chamber.

V96 strokes per minute.

angular positions of the arms 53 and pipes 26 may be changed relative to the actuating arms 41 to thereby adjust the angular positions of the several nozzles 27 carried by the pipes 26 relative to the surface of the web 11 in the etching chamber.

An indicator is provided for each of the oscillating spray pipes which shows atY all-times the degree of angular movement of the nozzles carried by the pipe above and below a middle position wherein the spray nozzles are disposed with the axes of the sprays perpendicular to the surface of the web in the chamber. The indicator may comprise ya dial 56 having a graduated periphery and an indicator hand 57 which, by reference to the dial, indicates the amplitude of the angular movement of the manifold pipe. As best shown in Figs. 5 and 9, the dial 56 is tixed on the end wall of the etching chamber 12 and the indicator hand 57 is operatively connected tothe pipe 26Y by a clamp 58. The dial 56 is calibrated in relation to the positions of the several nozzles 27 carried by the pipe 26 associated with the dial. As indicated in Fig. 9, the graduations may be in degrees with the zero position corresponding to the position of the nozzles 27 when the axes of the sprays emitted therefrom are horizontal or perpendicular to the surface of the web 11 in the etching chamber.

A modified form of mechanism for transmitting motion to the arms 41 is shown in Figs. 8 and 9 wherein the power-actuated mechanism for moving the spray nozzles is mounted above, rather than below, the etching chamber. Thus the actuating mechanism may comprise a power-driven disk 59 supported on a bracket 60 and suitable linkage connecting an eccentrically located pin 61 carried by the disk to the several arms 41. This linkage may comprise a link 62 extending from the pin 61 to a lever arm 63 which is pivotally supported at 64 on the frame of the machine and a second, angularly disposed lever arm 65, the free end of which is joined by a link 66 to one of the arms 41. A link 67 extends downward pipes 26 are oscillated about their axesu Operation In operation the web 11 is continuously moved at a controlled rate of speed along the guides 18 and 19 through the etching chamber 12 by power applied to the pressure rolls 17. The electric motors for actuating the pump delivering the etching iluid under pressure to the nozzles and for continuously moving the nozzles are also continuously operated during the etching treatment. Each succeeding portion of the web is thereby subjected to precisely the same etching treatment for a period of time which is determined by the rate of Etching uid of suitable composition, e. g., ferric chloride of density 42 Baume, preferably at an elevated temperature of hetween degrees and l40degrees F. is continuously sprayed upon the exposed areas of the web from the nozzles 27 carried by each of the Ymanifold pipes 26. The nozzles are continuously oscillated crosswise of the `direction of travel of the web at fairly high speed, e. g.,

As a result of this lateral movement of each nozzle, unusually rapid and uniform etching of all of the minute exposed areas of the web is obtained.

By directing the high velocity spray emitted from each nozzle alternately upward and then downward obliquely across the web surface, I eliminate localized passivity of the etching fluid at the several elementary areas to be etched and I also preventthe lodging of minute gas bubbles which are formed during the etching reactionin `theweb apertures or recesses as they are formed. fSuch `localized passivity and -lodging of 4gas bubbles aret the principal causes of retarded, non-uniform etching -where the other-essentials, including the concentration and temperature of the etchant, duration of thetreatment vand distribution of the etchant over the areas to be etched, are under proper control.

Experience has shown that, once the angleof oscillation of the several nozzles 27 is properly adjusted, reliable and uniform results are thereafter obtained. The necessary adjustments may be made quickly and easily, -without discontinuing the etching operation, merely by `suitable manipulation of the adjusting screws 52 which .severally determine the angular position of the nozzles .by the upper manifold 26 at each side overlaps the area of the web covered by the sprays from the nozzles carried by the lower manifold 26 at each side. Each nozzle 27 is preferably designed to deliver a solid conical spray of suitable width such as that indicated by the angle 72 in Figs. 9 and l0.

By imparting to the nozzles an amplitude of movement above the horizontal position which is greater than the amplitude of the movement below the horizontal position, I offset the undesirable effect of excessive flow of :etching fluid by gravity downward over the areas to be .etched and thus eliminate the tendency of such downward flow to elongate the several etched apertures vertically.

My improved apparatus and method herein described has been used, for example, in the manufacture of aperture masks for color television tubes from copper, nickel and super nickel metal webs of thicknesses within the range .004 to .008 inch thick and up to approximately 2 feet in width. For the production of super nickel masks of .008 inch thickness, an etching ychamber or zone approximately feet 3 inches long containing two rows of the etching nozzles at each side of the path of the web, as indicated in the drawing, has been used with excellent results. In this operation the web of .008 inch thickness and about two feet in width was moved through an etching chamber of the length indicated at the rate of approximately 25 inches per minute, while a ferrie chloride solution of density Baume 42 degrees and at a temperature of 12S-135 degrees was supplied to the spray nozzles 27 under 20 pounds per square inch pressure and the nozzles were oscillated at a rate of about 96 strokes per minute. Uniform apertures of .O1 inch diameter within a permissible tolerance of plus or minus .0005 inch were thereby obtained in closely spaced relation one to another over the area of the masks.

It will be evident that the improved etching apparatus and method herein described is primarily designed to produce apertures in metal webs by etching simultaneously from opposite sides of the web, identical designs in exact registry on opposite sides, having been formed previously in an etching resistant coating on each side. However, both thin. metal webs and other blanks may be etched from one side only without departing from the spirit of my invention and for some types of work it is not necessary that the etching shall be continued until the etched design extends completely through the metal. Where only one side of the blank or web is to be etched, the other side may be masked with a suitable etching resistant coating and the oscillating nozzles are used at l.one side `only -to apply the-etching: fluidto tthe-work sur face.

`Iclaim: p 1.Inetching apparatus kfora thin, elongated metal web having exposed areas Aand masked `areas defined l by c an :etching resistantcoating, .the improvements which cornprise, `means for moving said-web longitudinally and continuously through and beyond an etching-zone, spray nozzles .operativein saidA zone to-.cause` etching fluid to impinge -against -said\ areasof. the -continuously Vmoving web, means for continuously oscillating said nozzles crossways of the direction of movementY of the web and ata relatively high speed in said Vzone-and means-for adjusting -the amplitude of the oscillating movement of said nozzles. V2. In etching apparatus for a metal blank having exposed areas and masked =areas dened-by anv etching resistant coating, the improvements which-comprise, means for moving said blank through `an etching zone at afcontrolled rate of speed,`et ching means including spray nozzles opervative in said zone to cause etchingiluidto `impinge against said areas of thecontinuously moving blank and means for continuously moving said spray nozzles at a relatively high speed in alternatelyv opposite directions relative to the blank in said zone, whereby the etching Huid is caused to sweep across the blank.

3. In etching apparatus for a metal blank having exposed areas and masked areas defined by an etching resistant coating, the improvements which comprise, `means for moving said blank through an etching zone ata controlled rate of speed,etching means including spray nozzles operative in `said zone to'cause etching iluid to impinge against said areas of the moving blank and means for continuously imparting oscillating movement to said spray nozzles and at vrapidly changing angles relative to the surface of said `blank whereby the .etching uid is caused tosweep across the blank and to impinge against said areas of the blank lat continuously changing angles and in alternately opposite directions.

4. In etching apparatus for anelongated metal web .having exposed areas and masked areas defined by Yan Yetching resistant coating on at least one side thereof, Ythe improvements which comprise, means -for moving said web longitudinally with one longitudinal edge above the other through an etching -zone at a controlled rate of speed, etching means including spray nozzles operative in said zone to cause etching fluid-to impinge against said areas of the continuously moving web, and -means .for continuously oscllatng sad spray 'nozzles through rapidly changing angles relative tothe surface of said web whereby the etching fluid is caused to lsweep across vthe web and to impinge against :said areas thereof :at

continuously changing angles.

5. In etching apparatus for an elongated metal web having exposed areas and masked areas defined by an etching resistant coating on at least one side thereof, the improvements which comprise, means for moving said web longitudinally with one longitudinal edge above the other through an etching zone at a controlled rate of speed, etching means including spray nozzles operative in said zone to cause etching lluid to impinge against said areas of the continuously moving web, and means for continuously oscillating said spray nozzles transversely of the direction of movement of said web in said zone and through rapidly changing angles relative to the surface of said web whereby the etching fluid is caused to sweep across the blank and to impinge against said areas of the blank at continuously changing angles.

6. In etching apparatus for an elongated metal web having exposed areas and masked areas deiined by an etching resistant coating on at least one side thereof, the improvements which comprise, means for moving said web longitudinally in a substantially vertical plane with one longitudinal edge above the other through an etching zone at a controlled rate of speed, etching means including spray nozzles operative in said zone to cause tinuously moving web, and means for continuously moving said spray nozzles at a relatively high speed alternately upward and downward, transversely of the direction of movement of said web and in planes which are perpendicular to the web in said zone whereby the etching tiuid is caused to sweep across the web upwardly and downwardly.

7. In etching apparatus for anelongated metal web having exposed areas and masked areas defined by an etching resistant coating on at least one side thereof, the improvements which comprise, means for moving said web longitudinally with one longitudinal edge above the other through an etching zone at a` controlled rate of speed, a substantially horizontally disposed pipe extending in parallel relation to a face of the web in said zone, said pipe being supported for oscillating movement about its axis, a spray nozzle carried by said pipe and disposed to direct etching fluid against said areas of the continuously moving web in said zone, means for supplying etching uid under pressure to said pipe, and means for continuously oscillating said pipe about its axis at a relatively high speed whereby etching uid from said nozzle is caused to sweep across the web and to impinge against said areas thereof at continuously changing angles.

8. In etching apparatus for an elongated metal web having exposed areas and masked areas defined Yby an etching resistant coating on at least one sidethe'reof, the improvements which comprise, means for moving said web longitudinally with one longitudinal edge above the other through an etching zone at a controlled rate v of speed, a plurality of horizontally disposed' pipes'extending in parallel relation to a face of the web, one above another, in said zone, said pipes being supported for oscillating movement about their axes, a plurality of .Y

spray nozzles carried by each of said pipes and spaced apart one from another longitudinally of said zonesaid Vimprovements whichcomprise, means for moving "said web longitudinally with one longitudinal edge above the other through an etching zone at a controlled rate of speed, a plurality of horizontally disposed pipes extending in parallel relation to both sides of the web in said zone, said pipes being supported for oscillating movement about their axes, a plurality of spray nozzles carried by each of said pipes and disposed to direct etching iiuid against said areas of the continuouslymoving web at both sides thereof, means for supplying etching fluid under pressure to said pipes, and means for continuously oscillating said pipes, about their axes whereby etching uid from said nozzles is caused to sweep across the web and to impinge against said areas thereof at continuously changing angles.

l0. The method oflforming predetermined patterns of minute depressions in a metal blank having exposed areas and masked areas defined by an etching resistant coating which comprises, continuously moving said blank along a determined path at a predetermined speed causing an etching fluid in the form of uid pressure induced sprays Vto impinge against said areas of the blank at continuously and rapidly changing angles and in alternately opposite directions relative to the surface of the blank and continuing such movement of the blank and etching treatment until the etched areas have penetrated to a predetermined depth inthe blank.

11. The method in accordance with claim 10 wherein the metal blank is supported in a substantially vertical plane and is moved substantially horizontally along said path while the etching fluid is caused to impinge against said areas of the blank with alternately upward and downward sweeping motion. Y v

12. The method of forming predetermined patterns of perforations in an elongated metal web having exposed areas and masked areas defined by an etching resistant coating which comprises, continuously moving said web endwise along a determined path at a predetermined speed causing an etching uid in Vthe form of Vuid pressure induced oscillating sprays to impinge against said areas of theimoving web, and rapidly changing the direction of impingement of said sprays transversely ofthe direction of movement of the web along said path.

References Cited in the file of this patent UNITED STATES PATENTS 721,445 Holmstroni Feb. 24, 1903 979,071 Holmstrom Dec. 20, 1910 1,207,774 Levy Dec. 12, 1916 2,141,020 Robertson Dec. 20, 1938 2,261,988 Gaebel Nov. 11, 1941 2,321,982 Bracket June 15, 1943 2,570,299 Zademach et al Oct. 9, 1951 2,733,999 Rodman Feb. 7, 1956 

